Chapter 2: Group Consensus
- What are the key chapter elements (take home messages) that I should test you on?
- What new things are you curious about and/or did not fully understand
- What is the coolest thing you learned?
We are on leading edge of the space time continuum

How do you view the timeline of the history of life on Earth?


- Biased towards human existence?
- What processes are key? Is tempo (time between events) important?
- Something non-science based?
-
Perspective matters: Understanding the history of biodiversity and critical landmarks in life on Earth help us analyze current changes on Earth
The Earth is old…and it took a while for life to form.
- Surface was way too hot to start
- cooled enough to make a solid crust
- cooled enough sustain liquid water
- An atmosphere needed to form
- Without an ozone layer, radiation from sun was too intense
- Oxygen needed to accumulate for animals
- Lots of inorganic molecules but no organic molecules
- early atmosphere was reducing

Miller & Urey experiments


Origin of herdity was key for contempoary life
- Somewhere between the formation of RNA and cellular life a mechanisms to pass genetic information from partent to offspring emerged (heredity)
- Heredity is the key for evolution of life and biodiversity
- replication → variation → competition → natural selection
- mutations (replication mistakes) are the unit of variation
- Heredity likely took place in early ‘protocells’ with compartmentalized RNA
- have not been re-created in the lab

Cellular life begins ~3.5 billion years ago (key events)


Single-celled organisms altered the evolutionary landscape


Why did the Cambrian period explode?


Most groups of organims (still in ocean) evolve around Cambrian

